'Scan-negative' cauda equina syndrome: Evidence of functional disorder from a prospective case series.

In the first prospective comparison of 'scan-negative' (n=11) and 'scan-positive' (n=7) patients with cauda equina syndrome (CES) we found that Hoover's sign of functional leg weakness but not routine clinical features differentiated the two groups (p<0.02). This offers a new direction of study in this area, although magnetic resonance imaging is still required for all patients with possible CES.